The right-hander, fighting only his ninth bout as a professional boxer, was taken to hospital last Saturday after rallying from two early knockdowns to salvage a majority draw against fellow Filipino Mark Joseph Costa.

Maquinto, 8-0-1 with six wins by knockout, collapsed after the four-round bout in northern Manila.

Rhoby Orata, another member of the hospital medical staff, told ABS-CBN television in an interview that Maquinto was diagnosed with brain swelling, with a blood clot also detected at the right side of his brain.

"From the start Karlo's prognosis was not good," Orata added.

He could not be reached by AFP on Saturday.

Boxing is an extremely popular sport in the Philippines, which has two reigning world champions in welterweight Manny Pacquiao and bantamweight Nonito Donaire.

Pacquiao, who is also a member of the Philippine parliament, is regarded as one of the greatest boxers in history, amassing a 54-3 win-loss record with two drawn bouts. He holds a record eight world titles in as many weight divisions.